There are semiconductor modules, inside which there is provided an insulating substrate 102 that requires to be electroconductively connected with an external circuit by external output terminals 101 which are wired from an external circuit (not illustrated), as shown in FIGS. 13(a), 13(b). FIG. 12 shows a semiconductor module 100 of this type. In this semiconductor module 100, cylindrical contact components 103 are soldered in advance to a predetermined plurality of locations on the insulating substrate 102, and a plurality of external output terminals 101 having a corresponding arrangement are inserted respectively into the central holes of the contact components 103. These external output terminals 101 are connected to a semiconductor chip 104 (device chip, circuit chip), or the like, by aluminum wires 105, or the like. Moreover, the insulating substrate 102 is mounted on a metal substrate 109 and is covered with a resin case 108 which is fixed on top of the metal substrate 109. When the contact components 103 are soldered onto the insulating substrate 102, it is very important for the solder to maintain stable strength over a long period of time. Therefore, as indicated by the perspective view in FIG. 14, the conventional contact components 103 are each provided with a flange 106 of large diameter so as to increase the surface area of the end face of the cylinder, in order to stably stand the components 103 at the predetermined plurality of locations on the insulating substrate 102, as well as to ensure the solder junction strength. Moreover, a concave portion 107 which forms a solder reservoir section when forming the junction and which can ensure a predetermined thickness of solder is formed in the end face 106a of the flange 106 (Patent Document 1).
FIG. 6 shows a cross-sectional view along the line A1-A2 following the axis of the cylindrical shape of the contact components 103 in FIG. 14. In FIG. 7, a contact component 103a, similar to the contact components 103 in FIG. 6, having a structure in which a curve 110 (radius of curvature 0.1 mm) is applied to the edge at the end of the cylinder is shown in the cross-sectional view. Paste solder is used to affix the contact components 103, 103a of this type to the predetermined plurality of locations on the insulating substrate 102. For example, paste solder is printed in the arrangement pattern of the predetermined plurality of contact components 103 on the insulating substrate 102, and a heating process is applied to affix the contact components 103 while applying a predetermined load to the end faces of the flanges 106 of the contact components 103.
In this way, when soldering the end faces of the flanges 106 of the contact components 103 to the insulating substrate 102, the solder 111 pressed against the inner diameter side of each flange 106, of the solder 111 on the lower side of the flange 106, enters into the concave portion 107 inside the flange 106, as shown in FIG. 5, filling the inside of the cylinder, forming a layer of solder 111 having a thickness of several hundred microns, and thereby enhancing the junction strength. On the other hand, the junction strength is also increased due to the solder 111 which is pressed against the outer sides of the flanges 106 forming solder fillets 111a having a height corresponding to the thickness of the flange 106.
Inside the cylinder of each of the contact components 103 in the semiconductor module 100, the thickness of the solder inside the cylinder is limited to no more than approximately 500 μm in order to guarantee the insertion depth of the external output terminal 101 which is inserted in order to connect electroconductively with an external circuit. Moreover, the outer diameter of the external output terminal 101 is set to be close to the inner diameter of the cylinder, in order to ensure an electroconductive contact when the terminals are inserted inside the cylinders of the contact components 103. In order to ensure this electroconductive contact, desirably, the terminal is shaped as a quadrilateral rod to be inserted into the cylindrical hole.
Other prior art documents relating to the technology described above disclose technology for preventing the climbing up of solder in the lead terminals of an IC (integrated circuit device) (Patent Documents 2 and 3). Technology has also been disclosed which prevents the climbing up of solder inside hollow terminals (Patent Document 4).
Patent Document 1: US2009/0194884 A1 (FIGS. 1, 4 and 12)
Patent Document 2: Japanese Patent Application Publication No. 1989-315167 (“Function”)
Patent Document 3: Japanese Patent Application Publication No. 2012-199340 (Background Art)
Patent Document 4: Japanese Patent Application Publication No. 1994-020735 (Abstract, Object)